This invention relates to methods for nucleic acid amplification, including the polymerase chain reaction (PCR, U.S. Pat. Nos. 4,683,195 and 4,683,202), the ligase chain reaction (European Patent 320,308) and procedures using RNA polymerase driven amplifications (U.S. Pat. No. 4,786,600 and International Patent PCT/W091/02818).
Diagnosis of human disease has been aided by recent developments in nucleic acid amplification. These methods generate million to billion fold and more copies of a target sequence. Other nonspecific or specific products are also produced, some of which are produced from the primers, e.g., primer dimers in a typical PCR reaction. Such reaction products are potential inhibitors of the desired amplification process. After amplification, the product of the procedure is analysed by hybridization and then discarded. During these processes contamination of laboratory devices, the laboratory bench and other structures may result. This creates a problem in future amplification procedures since the methods are sensitive enough to detect even minute amounts of nucleic acids. In order to solve this type of contamination or cross-contamination problem, several methods have been devised.
For example, a PCR amplified product can be deactivated from further amplification by irradiation with UV light (Ou et al., 10 BioTechniques 442, 1991; Cimino et al., 19 Nucleic Acids Res. 99, 1991). Such irradiation in the absence or presence of a DNA binding photoactivatable ligand (e.g., isopsoralen) makes the product DNA nonamplifiable but retains the specific hybridization property. In addition, use of a 3'-ribose primer in a PCR reaction produces nucleic acid which can be readily destroyed by alkali. Similarly, other procedures are used to produce specific modified nucleic acids which can be selectively destroyed by treatment with a specific enzyme. Such modified nucleic acids have been produced by amplification in the presence of dUTP as a substrate in a PCR reaction. Deoxy-U containing product DNA can be degraded by a U-specific enzyme making the DNA nonamplifiable (Integrated DNA Technologies Technical Bulletin, Triple C primers 1992; Longo et al., 93 Gene 125, 1990). Many of these methods function well with DNA or its amplified DNA products. These methods, however, require expensive reagents and affect the course of the amplification method, e.g., by requiring longer time and specific conditions.
An object of the present invention is to obviate such problems and to develop simple reagents which are highly efficient in destroying nucleic acids and related amplification products which are potential inhibitors of other amplification reactions.